Paleoenvironmental changes in the northern area of the East China Sea during the past 42,000 years
Paleoenvironmental changes in the northern area of the East China Sea during the past 42,000 years
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DOI：
10.1016/j.palaeo.2004.12.028
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发表时间：
2005-04-18
影响因子：
3
通讯作者：
Huang, CY
中科院分区：
文献类型：
--
作者：
Ijiri, A;Wang, LJ;Huang, CY
对东中国海北部一个长33.65m、沉积速率极高(约80 cm/kyr)的岩心(MD982195)，每隔10 cm(约125年)分析了红色球藻的氧碳同位素、烷烃的海表面温度(SST)和浮游有孔虫组合的主成分分析。三角洲(18)O曲线的总体模式类似于烯酮SST曲线，类似于标准的开阔大洋氧同位素曲线。它显示了许多明亮的8180峰，显然对应于格陵兰冰芯过去42ka的Dansgaard-Oeschger(D-O)旋回。岩心顶部的烷酮类海温为24℃，与核心区周围的现代年平均海温相近。另一方面，末次冰盛期(LGM)的海温比现在低约5摄氏度。烯酮衍生的SST与对应于D-O旋回的光负(18)O峰不相关。根据赤潮和烯酮SSTs的氧同位素，表层水域的氧同位素比值表明，在末次盛冰期平均增加了1.0%，在温暖的D-O事件中出现了许多光峰。这表明，在这些事件期间，向核心区供应了淡水。通过对浮游有孔虫组合的Q型因子分析，将浮游有孔虫组合划分为4个时期：(1)42~24ka的强上升期，以球状有孔虫的大量出现为标志；(2)冷、低盐度水团时期(24ka~14ka)，主要表现为厚新球藻(Neogloboquarma Pachyderma)、新球形藻(Neogloboquina Incompanta)和五球藻(Globigerina Ququieloba)的增多；(3)冷水团向暖水团的过渡时期(14~8ka)8ka以后暖水物种的增多，以及(4)现今的暖黑潮条件。黑潮自末次42ka以来流入ECS，并在末次冰盛期(LGM)由于ECS北部沿岸水的扩张而减弱。(C)2005 Elsevier B.V.保留所有权利。
A 33.65-m-long IMAGES (MD982195) core with very high sedimentation rate (ca. 80 cm/kyr), retrieved from the northern part of the East China Sea, was analyzed at 10-cm intervals (about 125 years) for oxygen-carbon isotope of Globigerinoides ruber (sensu stricto), sea surface temperature (SST) from alkenones (U-37('K)), and principal component analysis of planktonic foraminiferal assemblage. The general pattern of the delta(18)O curve, resembling the alkenone SST curve, is similar to the standard open ocean oxygen isotope curve. It reveals many light 8180 peaks apparently corresponding to Dansgaard-Oeschger (D-O) cycles as observed in Greenland ice cores for the last 42 ka. The alkenone SST at the core top is 24 degrees C, which is close to the modem annual mean SST around the core site. On the other hand, SST during the last glacial maximum (LGM) was about 5 degrees C lower than that in the present day. Alkenone-derived SST does not correlate with the light negative delta(18)O peaks corresponding to the D-O cycles. The oxygen isotope ratios for the surface waters, based on oxygen isotopes of G. ruber and alkenone SSTs, indicate approximately 1.0% increase on average during the LGM and many light peaks at the warm D-O events. This suggests that fresh water was supplied to the core site during these events. The meandering of the westerlies during the cold and warm D-O cycles would have caused an atmospheric tele-connection between East Asia and Greenland.The core was divided into four periods based on Q-mode factor analysis of the planktonic foraminiferal assemblage, i.e. (1) a strong upwelling period from 42 to 24 ka, indicated by abundant occurrence of Globigerina bulloides, (2) a cold and low salinity water mass period from 24 to 14 ka, suggested by increase of Neogloboquadrina pachyderma, Neogloboquadrina incompta, and Globigerina quinqueloba, (3) a transitional period from cold to warm water masses from 14 to 8 ka, as indicated by the increase of warm water species such as Pulleniatina obliguiloculata and Globigerinoides ruber, and (4) the present-day warm Kuroshio Current condition after 8 ka. The Kuroshio Current flowed into the ECS since the last 42 ka and weakened during the last glacial maximum (LGM) due to the expansion of the coastal water in the northern part of the ECS. (c) 2005 Elsevier B.V. All rights reserved.